Valentine’s Day, Cetacean Style

In blue whales, amongst the selection criteria used by a female are the agility and strength of her male partner. In fall, blue whales passing through the St.Lawrence take part in a race between males to gain the affection of their sweetheart and stay in close proximity to her. This race was nicknamed the “rumba” by researcher Richard Sears. Two males will swim side by side without hesitating to jostle their opponent in a battle for the right to pass along their genes. They use their tails and pectoral fins to give one another an occasional shove in an attempt to gain the upper hand in the contest. The winner will stay with his female partner for several days, or even several weeks. It remains to be proven with certainty that their companionship will result in copulation every time.

Humpbacks are well-known minstrels during the breeding season. Although this behaviour has been studied at length, scientists cannot say with certainty that singing is part of a male’s courting attempts. It is the males that sing these songs, in addition to performing 5-metre-high breaches and slapping the water surface with their pectoral fins. Between the vocals and the percussion, one can say that humpback bulls are blessed with rhythm for seducing females! This is crucial, because the individual must stand out from other males, who are also stepping up their efforts to gain the favours of the female.

A study of humpback melodies shows that they use different sequences and various tones. Research results do not systematically converge toward the same conclusions, which makes it difficult to determine the exact significance of these sequences. All the same, they are unique compositions, comparable, in human terms, to a serenade.

Research conducted by the Group for Research and Education on Marine Mammals (GREMM) has provided important insight into the social activities of male belugas in the St. Lawrence. Reaching their sexual maturity between 16 and 18 years old, males create “friendship” bonds where social-sexual games play an important role.

Thanks to drone images shot over the St. Lawrence Estuary, GREMM Scientific Director Robert Michaud and his team were able to observe male belugas exchanging curious pelvic thrusts. Practice for mating? Strengthening of social ties? To be continued!